Tiltable x-ray examination table structure



March 15, 1966 J. DOUGALL 3,240,935

TILTABLE X-RAY EXAMINATION TABLE STRUCTURE Filed May 16, 1963 4Sheets-Sheet 1 )n/VENToR JOHN 8 MM+QMM March 15, 1966 J. DOUGALL3,240,935

TILTABLE X-RAY EXAMINATION TABLE STRUCTURE Filed May 16, 1963 4Sheets-Sheet 2 ,Mswma J. DOUGALL March 15, 1966 TILTABLE X-RAYEXAMINATION TABLE STRUCTURE 4 Sheets-Sheet 5 Filed May 16, 1963 vNEA/ToR IOHA/ DDUGALL J. DOUGALL March 15, 1966 TILTABLE X-RAYEXAMINATION TABLE STRUCTURE 4 Sheets-Sheet 4 Filed May 16, 1963 JbH/V000% L L United States Patent 3,240,935 TILTABLE X-RAY EXAMINATION TABLESTRUCTURE John Dougall, Gillnock, Scotland, assignor to AssociatedElectrical Industries Limited, London, England, a British company FiledMay 16, 1963, Ser. No. 280,957 Claims priority, application GreatBritain, May 18, 1962, 19,303/ 62 3 Claims. (Cl. 250-55) This inventionrelates to tiltable table structures particularly but not exclusively tosuch structures as used for supporting patients for X-ray diagnosis orexamination.

In a common form of tiltable X-ray table structure as used in hospitals,provision is made for mounting a viewing screen above the table inalignment with an X-ray tube below the table (considering the table inits horizontal position) and for permitting the aligned screen and tubeto be moved both lengthwise and transversely of the table so as -tobring. the screen into any desired position over a person lying on thetable.

Provision is usually also made for interposing a loaded X-ray filmcassette between the patient and the screen so as to obtain a radiographof the X-ray image, and further provision may be made for bringing anover-table X- ray tube into position (the screen being moved out of theway) and taking a radiograph with a film cassette brought into alignmentbeneath the table. In order to enable a patient to be examined not onlywhen lying horizontally but also in other positions including verticallyupright (or nearly so), the table may be tiltable about a transverseaxis between a vertical tilting limit in which it is inclined verticallyupright and a reverse tilting limit in which it has a reverseinclination. Some tables are made which can be tilted to a verticallyupright position in the reverse direction as well as in the verticaldirection, but usually a maximum reverse tilt of about 45 would beacceptable.

In designing a tiltable table with under-mounted X-ray tube or otherequipment, a compromise has to be struck between certain mutuallyconflicting desiderata. Firstly it is desirable to keep the table as lowas possible in order to facilitate getting on and off and also tofacilitate viewing of an over-table screen, the minimum height of whichin the horizontal position of the table will be determined by the tableheight. In order to obtain a desired image size on the screen with aminimum angle divergence of the X-ray beam from an under-table tube, itis also desirable to have the X-ray tube as far below the table aspossible, but this conflicts with the requirement for minimum tableheight and the spacing of the tube from the underside of the table isfurther restricted because of the necessity of ensuring that, with thetube at either extreme of its lengthwise travel, the tube will remainclear of the floor when the table is tilted.

To permit the table to tilt to a vertically upright position, the heightof the tilting axis has to be sufi'icient to ensure that the loweringend of the table remains clear of the floor during tilting: the heightof the axis is therefore a function of the distance between it and thetable end, and for this reason the table may be arranged for forward andreverse tilting about ditferent axes respectively nearer the oppositeends of the table. However the closeness of the tilting axis to an endof the table is restricted not only by considerations ofcounter-balancing but also by the desirability of keeping to a minimum,for convenience of the operating staif, the increase in viewing screenheight as the table is tilted: this means keeping the rise of the tableitself to a minimum at the position along it at which the screen is mostoften used, which is over a patients chest. On tilting about an axis toonear 3,240,935 Patented Mara 15, 1966.

the foot end of the table, the rise of the table at the screen position,and therefore the screen height, would increase considerably with angleof tilt especially through the initial part of the tilt.

An object of the invention is to provide an improved tiltable tablearrangement which permits the foregoing desiderata to be more nearlysatisfied as regards horizontal table height, distance below table atwhich an X-ray tube or other equipment can be mounted, and rise of tableat an intermediate position on tilting- According to the invention thereis provided a tiltable table structure in which the table is pivotedabout a transverse tilting axis on a support lever which is itselfpivoted about another axis preferably also transverse to the table andhorizontally further from one end of the table than is the tilting axis,namely so that the distance of the lever axis from that end of thetable, measured horizontally when the table is horizontal, is greaterthan that of the tilting axis from that end. Means is provided fortilting the table forward about its axis on the lever so that one endswings down (being the end already referredto when the lever axis istransverse) and further means effective at least during the later partof the forward tilting is provided for pivoting the lever about its axisin such sense as to raise the tilting axis. As a resultthe forwardtilting takes place accompanied at least in the later stages by araising of the tilting axis. This means that at what would otherwisehave been a limiting position of forward tilt because further tiltingwould have caused the lowering end of the table or under-mountedequipment to hit the floor, the tilting can be continued because theraising of the tilting axis can keep the table and under-mountedequipment clear of the floor. Consequently in the horizontal positionthe tilting axis can be lower than it could have been if fixed, so thatthe table can also be lower. Also the tilting axis can be further fromthe lowering end of the table than would otherwise be the case, so thatthe rise of the table at anintermediate position in its length (such aswould cor-respond for instance to a chest examining position of an X-raytable viewing screen) will be commensurately less for a given angle oftilt. With the lever pivoted on a transverse axis and inclining upwardlyfrom this axis to the table axis, as is preferred, the raising of thetable axis by the pivoting of the lever'will be accompanied by areduction of the distance between the two axes as measured horizontally,an eflect which becomes more pronounced as the table comes nearer to itsvertical position. This has the effect of drawing in the table towardsthe position of the lever axis so that, in the case of an X-ray tablefor instance, less end wall clearance will be required to permit frontalobservation of a viewing screen when the table has been forwardly tiltedto or near the vertical. Also less change of position is required of theoperator between the horizontal and vertical table positions.

With the lever pivoted on a transverse axis, reverse tilt of the tablefrom horizontal can be achieved by pivoting the lever alone whilemaintaining a fixed angular orientation between it and the table.

While the means for tilting the table and pivoting the lever about theirrespective axes may have separate prime movers, for instance separatepneumatic or hydraulic jacks, it is possible and advantageous to have asingle jack or other prime mover acting on both through suitablemechanical linkage. Co-ordination of the operation of the two means canalso be achieved by such a linkage: for instance a link actuated byforward tilting of the table may itself actuate a secondary lever which,at least after a predetermined table inclination has been reached (forinstance an inclination such that the lowering end of the table or anunder-mounted equipment is closely approaching the floor), acts on themain lever so as to cause it to pivot about its axis and thereby startto raise the table axis. For this purpose the secondary lever may bepivoted to the main lever and may, at a predetermined point in thetilting, engage an abutment which, by its reaction on the secondarylever combined with the actuating force in the link referred to, causesthe required pivotal movement of the main lever.

An embodiment of the invention incorporating such a linkage arrangementis illustrated by way of example in the accompanying drawings in whichFIG. 1 is a general perspective rear view of a tiltable X-ray tablestructure embodying the invention and FIGS. 2-5 are front views showingthe tilting mechanism of the table in various positions. FIG. 2 showsthe mechanism in the horizontal position of the table, FIG. 3 shows itwith the table in a partially forwardly inclined position, FIG. 4 withthe table tilted fully forward to a vertical position, and FIG. 5 withthe table tilted to the limit of its reverse tilt.

FIG. 1 shows the general arrangement of a tiltable X-ray table structureembodying the invention. The table 1 shown in its horizontal position isfully cantilevered and is supported only at the rear, where it has anattachment bracket 2 (FIG. 2) connected to a supporting and tiltingmechanism housed in a pedestal 3. A cantilevered structure 4, whichcarries a viewing screen 5 and may also include a carriage (not shown)by which an X-ray film cassette can be moved into position beneath thescreen, is supported on legs 6 which are telescopically accommodated ina rear support 7. The support 7 is mounted on a structure (indicated inoutline only) which extends through a slot 9 in the rear of the tablestructure 1. This structure 10 carries an undertable X- ray tube 11 invertical alignment beneath the screen 5 and is rail-mounted for movementtransversely of the table on a carriage (not shown) which is itselfrail-mounted beneath the table top for movement lengthwise of the table.The structure 10 can therefore be adjusted in position both transverselyand longitudinally of the table, taking the X-ray tube 11 and screenstructure 4 with it. The assembly 4-5-7-1041 tilts with the table. Thescreen structure 4 can be removed by raising it so as to extract itstelescopic legs 6 from their sockets in the support 7, it beingcontemplated that for this purpose an overhead gantry may be providedrunning on rails so as to permit the structure 4 to be moved completelyclear of the table top. A further gantry on the same rails may carry anover-table X-ray tube which, with the screen structure 4 removed, can bebrought into vertical alignment with a rail-mounted film cassettecarriage (not shown) provided beneath the table top and movable alongthe length of the table. With gantria provided as aforesaid for thescreen structure 4 and an over-table X-ray tube it is contemplated thatthese items of equipment may be left suspended from their gantries whilein use over the table, being counter-balanced through their supsensionsto facilitate height adjustment. It will be noted that the front side ofthe table is completely clear of obstructions which could hinder orinconvenience operating staff at work. Also with the structure 4 removedaccess to the top of the table from the rear is virtually unobstructed.

In FIGS. 2-5 the screen structure 4 has been shown in a positionapproximating to that which it would occupy for chest examination. Inorder not to obscure the view of the tilting mechanism, the under-tableX-ray tube 11 and its supporting structure 10 have been omitted fromthese figures, but the extreme position of'the X-ray tube 11 at thelimit of movement of the assembly 4-5- 7-10-11 towards the foot end ofthe table has been indicated at 11'. The tilting mechanism has to ensurethat with the tube in this extreme position it Will not foul the floorif the table is tilted forward to its vertical up right position.

Corning now to the tilting mechanism, the attachment bracket 2 by whichthe table is carried is pivotally mounted on a tilting axis a near oneend of a main lever 12, which near its other end is itself pivotallymounted in the pedestal 3 on a fixed axis b. A piston operated ram 13 ispivtoally secured at its outer end to the bracket 2 at a position (0)such that on extension of the ram a turning moment about the axis a willbe applied to the bracket 2 such as to tilt the table in the forwarddirection. The rear end of a hydraulic or pneumatic cylinder 14accommodating the operating piston for the ram 13 is pivotally securedin the pedestal 3 on a fixed axis d. A secondary lever 15 intermediatelypivoted on the main lever, at e, carries a roller 16 at one end and atthe other end is coupled to the bracket 2 by a link 17. Link 17 ispivoted at one end to bracket 2 and is pivoted at its other end tosecondary lever 15. The disposition of this link is such that duringforward tilting it is actuated from the bracket 2 and urges the lever 15in a clockwise direction about the axis e.

The forward tilting action is as follows. Starting in the position shownin FIG. 1 admission of pressure to the cylinder 14 so as to extend theram 13 results in movement of the various parts of the mechanismaccording to the arrow-headed full lines. The bracket 2, and with it thetable 1, begin to be tilted forward about axis a. Link 17, afterinitially urging the lever 15 anticlockwise (namely until the linkpasses through the position at which it is radial to axis a) urges lever15 clockwise so that its roller 16 approaches a horizontal rollerway 18.When the roller 16 reaches the rollerway 18 the various parts of themechanism have the relative dispositions shown in FIG. 3, and it isarranged that this occurs when the under-table X-ray tube 11, if in itsextreme position 11', is just clear of the floor 19. The front end ofthe table is also still clear of the floor.

Continued extension of the ram 13 produces movements according to thearrows in FIG. 3. The table 1 continues to be tilted about its axis aand the link 17 continues to urge the lever 15 clockwise. However due tothe engagement of the roller 16 with the rollerway 18 the roller end ofthe lever 15 is constrained to move horizontally. Consequently the pivotaxis e of this lever on the main lever 12 is caused to rise, taking withit the main lever 12 which until now has remained stationary against astop 20. The lever 12 therefore pivots about its axis 11 away from thestop 20, progressively raising the tilting axis a and at the same timedrawing it in horizontally (towards the left in the figures). Theraising of the axis a combined with the continued tilting of the tableabout this axis causes the lower edge of the table to follow the locus21 and the lowest point of the X-ray tube 11 when in position 11 tofollow the locus 22, it being observed that both loci remain clear ofthe floor. The table finally reaches the vertically upright position asshown in FIG. 4 with the ram 13 fully extended.

Reverting to FIG. 2, admission of reverse pressure to the cylinder 14 soas to retract the ram 13 will produce movements as indicated by thearrow-headed dotted lines in this figure. The tendency of the bracket 2to be reverse-tilted about its axis a by the retraction of the ram 13 isprevented by a stop 23 which during the reverse tilting maintains afixed angular relationship between the table and the main lever 12.Retraction of the ram 13 therefore acts so as to pull the lever 12upwards about its axis b unaccompanied by tilting of the table about itsaxis a. Reverse tilting of the table structure about the lever axis btherefore takes place until as shown in FIG. 5 the limit of reverse tiltis reached with the ram 13 fully retracted.

Both forward and reverse tilting can of course be stopped and held atany intermediate inclination.

What I claim is:

1. A tiltable X-ray examination table structure comprising a supportbase; a table; a support lever on which the table is pivotally mountedabout a transverse tilt axis and which is itself pivoted on said supportbase about another axis; a linearly extensible operating member actingbetween said support base and the table, said operating member beingcoupled to the table at a point spaced from said tilt axis and beingactuatable to tilt the table in a forward direction of rotation aboutthe tilt axis; and a coordinating mechanical linkage connected betweenthe table and support lever comprising a secondary lever connected tothe support lever at a point removed from its pivot axis on the supportbase and a link connecting this secondary lever to a point on the tableremoved from said tilt axis, said link being responsive to tilting ofthe table in the forward direction to actuate the secondary lever andcause it, at least after a predetermined inclination of the table hasbeen reached, to pivot the support lever about its pivot axis on thesupport base in such sense as to raise said tilt axis.

2. A tiltable X-ray examination table structure comprising a supportbase; a table; a support lever on which the table is pivotably mountedabout -a transverse til-t axis and which is itself pivoted on saidsupport base about another axis; a linearly extensible operating memberacting approximately parallel to the support lever and having pivotalconnections by which it is connected between a fixed point on the saidsupport base and a point of connection to the table so located inrelation to said tilt axis as to permit tilting of the table in aforward direction of rotation from a horizontal position by variation ofthe effective length of said operating member in one sense; a secondarylever pivoted to the support lever at an intermediate point on each ofthese levers; a link connected between one end of the secondary leverand a point of connection to the table so located in relation to saidtilt axis that tilting of the table in said forward direction will causethe link to produce pivotal movement of the secondary lever in the senseto move the other end of this secondary lever downwardly; and agenerally horizontal abutment surface on said support base positioned sothat on continued pivotal movement of the secondary lever its saiddownwardly moving end will come into engagement with said surface withconsequent reaction on the secondary lever, said reaction raising thepivotal connection point of the secondary lever and support leverwhereby to pivot the support lever in the sense to raise said tilt axis.

3. A table structure according to claim 2, wherein in the horizontalposition of the table the effective length of said operating member isalso variable in the sense opposite to that for tilting the table in thetorw-ard direction, whereby to tend to tilt the table in the reversedirection, and said structure further includes stop means preventingsuch reverse tilting of the table with respect to the support leverwhereby such opposite sense variation of the length of the operatingmember is effective to tilt the table and the support lever together inreverse direction about the support lever pivot axis on said supportbase.

References Cited by the Examiner UNITED STATES PATENTS 2,568,236 9/1951Kizaur 250 2,680,046 6/1954 Stava 250- 55 2,872,584 2/1959 Schiring eta1 25055 3,069,543 12/1962 Sazavsky 25055 RALPH G. NILSON, PrimaryExaminer.

ARCHIE BORCHELT, Examiner.

1. A TILTABLE X-RAY EXAMINATION TABLE STRUCTURE COMPRISING A SUPPORTBASE; A TABLE; A SUPPORT LEVER ON WHICH THE TABLE IS PIVOTALLY MOUNTEDABOUT A TRANSVERSE TILT AXIS AND WHICH IS ITSELF PIVOTED ON SAID SUPPORTBASE ABOUT ANOTHER AXIS; A LINEARLY EXTENSIBLE OPERATING MEMBER ACTINGBETWEEN SAID SUPPORT BASE AND THE TABLE, SAID OPERATING MEMBER BEINGCOUPLED TO THE TABLE AT A POINT SPACED FROM SAID TILT AXIS AND BEINGACTUATABLE TO TILT THE TABLE IN A FORWARD DIRECTION OF ROTATION ABOUTTHE TILT AXIS; AND A COORDINATING MECHANICAL LINKAGE CONNECTED BETWEENTHE TABLE AND SUPPORT LEVER COMPRISING A SECONDARY LEVER CONNECTED TOTHE SUPPORT LEVER AT A POINT REMOVED FROM ITS PIVOT AXIS ON THE SUPPORTBASE AND A LINK CONNECTING THIS